The present invention relates to a system and method for controlling the quality of water in a recreational water installation such as spa, hot tub or pool.
The water quality of a recreational water facility depends on sanitation and chemical balance. In recreational water facilities where the water volume is fairly small, such as spas and hot tubs, proper sanitation and chemical balance largely depend on the number of bathers and the duration of use.
In pools, the challenges of keeping the water properly sanitized and balanced efficiently while maximizing user experience are magnified due to the larger volume of water and the affect on water quality of environmental conditions such as rain, wind and sun.
Bathers introduce most of the waste into the spa. This waste includes urea, sweat, bacteria and dead skin that the sanitizer must rapidly oxidize in order to prevent bacteria from proliferating and forming biofilms that are very difficult to eradicate. The number of bathers and length of use determine oxidizer consumption in the spa. For example, a typical 350 gallon spa will require 11 grams of dichlor sanitizer following use by two bathers soaking for 20 minutes while the same spa will require only about 1 g per day when not in use. Bathers prefer water that feels soft and smells ‘clean’ which requires low levels of sanitizer (typically 2-5 ppm). Thus, in spas, sanitizer should be applied immediately after use to oxidize the waste and then be kept at low levels so that the water feels ‘chemical free’ when the user enters the spa again. This is the challenge of spa maintenance and the reason it is difficult to properly sanitize the spa with steady state or scheduled introduction of a sanitizer.
Free chlorine is the most popular EPA recognized sanitizer. Chlorine is effective in killing bacteria and viruses leading to water turbidity if used at the right amount (1-4 ppm) and time. Chlorine sanitizer also oxidizes biological residues introduced by the users leading to foaming and produces chloramines that give the spa its ‘chlorine’ smell.
Proper maintenance of pH is also important for safety and comfort of spa users. Sweat, sanitizer oxidation, and aeration jets affect pH and lower alkalinity. The pH needs to be raised to maintain appropriate levels for the sanitizer to be effective and the water to feel comfortable. Sanitation products such as bromine tablets (Bromo Chloro Dimethyl MH—BCDMH), dichlor tablets both dispensed from a floater for sanitizer background level maintenance, biguanides without chlorine, and heavy metal filters (not EPA approved) all have issues requiring user intervention, high background sanitizer levels, costs or other side effects.
While reducing the present invention to practice, the present inventor has devised a sanitation system that can provide use-responsive sanitation of a recreational water facility such as spa. The present system can be used to maintain fresh smelling, comfortable spa water with minimal user intervention and while minimizing the use of sanitizers and other chemicals.